Spring blades for contact arms and the method for making the same

ABSTRACT

The disclosure is directed to a method of fabricating spring contact arm blades. A sheet of material is annealed on one side and thereafter deformed to provide screw threads. The sheet is cut to provide strips of the desired blade size and the deformed annealed portion is rolled to form a threaded tubular terminal portion.

United States Patent Koch et al.

[ 1 May 30, 1972 SPRING BLADES FOR CONTACT ARMS AND THE METHOD FOR MAKING THE SAME lnventors: Claude V. Koch, Two Rivers; Donald G.

I Storms, Manitowoc, both of Wis.

Assignee: AMF Incorporated Filed: July 27, 1970 Appl. No.: 58,610

US. Cl. ..113/l19, 339/263 R, 339/219 R Int. Cl... ..B2ld 53/00 Field of Search ..1 13/1 19; 10/86 R; 72/342; 339/219 R, 263 R; 200/166 BH, 166 J, 166 C; 29/D1G. 21, 630 C, 622

References Cited UNITED STATES PATENTS 10/1964 Richert et al ..200/l66 .1

Primary Examiner-Richard J. Herbst Attorney-George W. Price and Charles .1. Worth ABSTRACT The disclosure is directed to a method of fabricating spring contact arm blades. A sheet of material is annealed on one side and thereafter deformed to provide screw threads. The sheet is cut to provide strips of the desired blade size and the defomied annealed portion is rolled to form a threaded tubular terminal portion.

6Cla1ns, 1 Drawing n um Patented May 30, 1972 3,665,881

2 Sheets-Sheet 1 FIG}! INVENTORS CLAUDE V. KOCH DONALD 6. 5T RMS A ENT SPRING BLADES FOR CONTACT ARMS AND THE METHOD FOR MAKING THE SAME BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates to electrically conductive spring blades of the type used for spring contact arms and the method of making the same.

Spring contact arms are embodied in many types of switch means and the spring blades cause few problems when they are provided with plug-in terminals for making electrical connections as shown in US. Pat. No. 3,391,258 which issued July 2, I968 to P. R. Vimoche, .Ir., or when provided with terminals for soldered connections as shown in US. Pat. No. 3,443,047 which issued May 6, I969 to P. A. I-Ianold.

Problems are encountered when threaded fasteners are required for electrical connections. A common connection of this type is shown in US. Pat, No. 3,133,172, which issued May 12, 1964 to W. A. Williams al., in which the threaded fastener screws into an opening in the terminal. The effective length of the threads in this type of a connection are limited to substantially the thickness of the blade terminal. Altematively, mounting brackets may be connected to the ends of the blades and provide threaded opening for the fasteners as shown in US. Pat. No. 3,452, I65, which issued June 24, 1969 to R. D. Rulseh. However, the effective length of the threads is still limited and the cost of the blade is greatly increased.

Nut and bolt arrangements as shown in US. Pat. No. 2,106,595, which issued Jan. 25, 1938 to A. M. Draving, have been found to beacceptable in some instances, but costly.

Accordingly, an object of the present invention is to provide a spring contact arm blade with a terminal portion having a substantial length for threads to receive a threaded fastener.

Another object of the present invention is to provide the foregoing blade with an integral terminal portion.

And, another object of the present invention is to provide the foregoing blade which is formed at one end to provide the terminal portion.

Still another object of the invention is to provide the threads in the terminal end surface prior to forming the terminal portion.

And still another object of the present invention is to provide the foregoing spring blades capable of being made relatively inexpensively and with facility by automatic or semi-automatic machines.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings wherein several embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for illustration purposes only and are not to be construed as defining the limits of the invention.

FIG. 1 is a perspective view of a sheet or ribbon of electrically conductive spring blade material diagrammatically illustrating the heat treatment thereof;

FIG. 2 is a plan view of a spring contact arm blade, in accordance with the present invention, before the terminal portion is formed;

FIGS. 3 and 4 are side views of two spring contact arm blades made in accordance with the present invention;

FIG. 5 is an end view of the blade of FIG. 4;

FIGS. 6 and 7 are enlarged fragmentary sectional views taken on lines 6/6 of FIG. 3 and 7/7 of FIG. 4, respectively.

DESCRIPTION OF THE INVENTION Referring now to the drawings, an elongated sheet or ribbon 10 of electrically conductive spring material, as shown in FIG. 1, has an effective width between its lateral edges 11 and 13 which is substantially equal to the spring blades 20 to be made therefrom. The sheet or ribbon 10 is first heat treated by being fed axially, in the direction of the arrow in FIG. 1, past a heat chamber 15 for annealing one side of the material to be formed. The annealed area 14, determined by the extent of the material exposed to the heat of the chamber 15, extends inwardly from the lateral edge 11 of the ribbon I0 a predetermined distance as indicated by the line 12. The lateral dimension of the annealed portion 14 should approximate that part of each of the blades to be formed or rolled to provide a blade terminal 27.

The ribbon 10 is provided with a liquid bath 16 for cooling laterally of and past the heat chamber 15. Wiping means 17 is provided to remove the liquid from the ribbon 10 before it is rerolled or further worked on.

The spring contact arm blades 20 are laterally extending strips which are cut or blanked from the ribbon 10 either ad- 15 jacent to the heat treat site or at another location where required machines are available. One or more blades 20 can be blanked or cut from the leading end of the ribbon as it is being fed to a suitable machine.

As shown in FIG. 2, a hole or opening 23 is provided in the free end 22 of the blade 20. For this, a series of axially spaced holes 23 can be punched in the ribbon 10 adjacent its lateral edge 13 as the ribbon is being fed to the blanking machine. A]- ternatively, a hole or opening 23 can be suitably provided at the same time the blade is blanked.

Although not necessary when self-tapping terminal screws are to be used, it is preferred that the terminals or terminal portions 27 of the blades 20 be provided with internal threads 25 as shown in FIGS. 6 and 7. This can be accomplished by use of a roller die for progressively defonning one surface of the annealed portion 14 of the ribbon 10 as it is fed to a blanking machine to provide disjointed threads 25 in the flat blanks of the blades 20, as shown in FIGS. 1 and 2. Alternatively, the disjointed threads 25 may be provided during blanking of the blades 20.

When a flat blanked blade 20 is complete, as shown in FIG. 2, it comprises a main or operable blade portion 21 which has a freeend 22 with a contact face mounting opening 23. The blade 20 has an annealed portion 24, preferably with the disjointed thread 25, at its other end and spaced from the main blade portion 21 by a stepped intervening or shoulder portion 26 which will be further discussed.

The annealed end portion 24 is then rolled to one side of the normal plane of the blade 20 to form the tubular portion 27 as shown in FIG. 6. The threads 25 are disposed within the tubular terminal portion 27 and are now formed to accept a threaded fastener 31 at either end as shown in FIGS. 6 and 7. The rolling or forming of the annealed end portion 24 normally is sufficient cold working to harden the material so the tubular terminal portion 27 is not enlarged by the insertion of a threaded fastener 31. However, in some instances, further hardening may be required. 7

An L-shaped blade may be desired. For this, as shown in FIGS. 4 and 5, the blade 20 is provided with a bend 28 which offsets the terminal portion 27 and the adjacent blade portion 29 from the normal plane of the main blade portion 21.

Referring to FIGS. 6 and 7 when a spring contact am is mounted in a switch case as shown, described and claimed in our co-pending application, Ser. No. 58,609, filed Sept. 28, 1970, now U.S. Pat. No. 3,609,273, the shoulder portion 26 abuts a case wall 30 to space the main or operating blade portion 21. The tubular portion 27 extends past the shoulder portion 26 into an opening in the case wall 30 to provide the switch with an external connection capability as shown in FIG. 7. If an internal connection capability, as shown in FIG. 6 is desired, the opening in the wall 30 may be an internal socket recess.

Although several embodiments of the invention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes may also be made in the design and arrangement of the pans without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

We claim:

1. The method of fabricating spring contact arm blades comprising the steps of providing an elongated sheet of electrically conductive spring blade material, annealing one side of said sheet, deforming one surface of the annealed side of said sheet to provide threads in the tubular terminal portion of each strip, cutting said sheet laterally to provide a plurality of strips of predetermined size and shape each of which is annealed at one end, and rolling the annealed end of each of said strips to form a tubular threaded terminal portion. 2. The method of fabricating spring contact arm blades in accordance with claim 1, further comprising the step of making holes in the other side of said sheet to provide an opening for connecting a contact face adjacent the end of each strip opposite from said annealed end thereof. 3. The method of fabricating spring contact ann blades in accordance with claim 2, wherein said contact face mounting holes are provided in each of said strips at the time said strips are cut from said sheet. 4. The method of fabricating spring contact arm blades in accordance with claim 2, wherein the annealed surface at one end is deformed and the contact mounting opening is provided adjacent the other end of each strip when the strip is cut from said sheet. 5. The method of fabricatingspring contact arm blades in accordance with claim 1,

said sheet being fed axially past a heat chamber for annealing said one side, and providing a roller die in contact with a surface of the annealed side of said sheet to progressively deform the contacted surface as said sheet is fed to provide threads within said tubular terminal portion. 6. The method of fabricating spring contact arm blades in accordance with claim 5, further comprising the step of providing a cooling bath to the areas of said sheet disposed laterally of said heat chamber and between said heat chamber and said roller die.

I. l t i 10! 

1. The method of fabricating spring contact arm blades comprising the steps of providing an elongated sheet of electrically conductive spring blade material, annealing one side of said sheet, deforming one surface of the annealed side of said sheet to provide threads in the tubular terminal portion of each strip, cutting said sheet laterally to provide a plurality of strips of predetermined size and shape each of which is annealed at one end, and rolling the annealed end of each of said strips to form a tubular threaded terminal portion.
 2. The method of fabricating spring contact arm blades in accordance with claim 1, further comprising the step of making holes in the other side of said sheet to provide an opening for connecting a contact face adjacent the end of each strip opposite from said annealed end thereof.
 3. The method of fabricating spring contact arm blades in accordance with claim 2, wherein said contact face mounting holes are provided in each of said strips at the time said strips are cut from said sheet.
 4. The method of fabricating spring contact arm blades in accordance with claim 2, wherein the annealed surface at one end is deformed and the contact mounting opening is provided adjacent the other end of each strip when the strip is cut from said sheet.
 5. The method of fabricating spring contact arm blades in accordance with claim 1, said sheet being fed axially past a heat chamber for annealing said one side, and providing a roller die in contact with a surface of the annealed side of said sheet to progressively deform the contacted surface as said sheet is fed to provide threads within said tubular terminal portion.
 6. The method of fabricating spring contact arm blades in accordance with claim 5, further comprising the step of providing a cooling bath to the areas of said sheet disposed laterally of said heat chamber and between said heat chamber and said roller die. 